1. Elements

2. References

A trace radioisotope is a radioisotope that occurs naturally in trace amounts (i.e. extremely small). Generally speaking, trace radioisotopes have half-lives that are short in comparison with the age of the Earth, since primordial nuclides tend to occur in larger than trace amounts. Trace radioisotopes are therefore present only because they are continually produced on Earth by natural processes. Natural processes which produce trace radioisotopes include cosmic ray bombardment of stable nuclides, ordinary alpha and beta decay of the long-lived heavy nuclides, thorium-232, uranium-238, and uranium-235, spontaneous fission of uranium-238, and nuclear transmutation reactions induced by natural radioactivity, such as the production of plutonium-239^[1] and uranium-236^[2] from neutron capture^[3] by natural uranium.

Elements

The elements that are created only from decay are listed below.

Isotopes of other elements:

• Tritium
• Beryllium-7
• Beryllium-10
• Carbon-14
• Fluorine-18
• Sodium-22
• Sodium-24
• Magnesium-28
• Silicon-31
• Silicon-32
• Phosphorus-32
• Sulfur-35
• Sulfur-38
• Chlorine-34m
• Chlorine-36
• Chlorine-38
• Chlorine-39
• Argon-39
• Argon-42
• Calcium-41
• Iron-60

References

• John Shaffer (baseball)
• John Shagaya
• John Shakespeare Allison
• John Sham
• John Shanahan
• John Shand Kydd
• John Shanes
• John Shanley (bishop)
• John Shannon
• John shannon
• John Shannon (musician)
• John Shannon (novelist)
• John Shannon (politician)
• John Sharian
• John Sharp (archbishop)
• John Sharp, Archbishop of York
• John Sharp (British Army officer)
• John Sharp (disambiguation)
• John Sharpe (Australian murderer)
• John Sharpe (disambiguation)
• John Sharpe Griffith
• John Sharpe (tennis)
• John Sharples
• John Sharples (footballer, born 1934)
• John Sharples Jr.